Help with Dish alignment

Forums › Home Theatre (including HTPC and EPG Collector) › Help with Dish alignment - please!

slotherby

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#18184 31-Dec-2007 13:24

Hi

I have a Media Centre and want to get Freeview on it. I purchased a 90cm dish and 11300 Sharp LNB. I have tried to align it with my 'signal meter' but am having no luck, can anyone help?
I have borrowed my folks Sky STB (Pace DSR620) to get the dish sorted before I attempt the MCE.

I have ensured that the LNB settings look correct : Power - ON, Tone - None, Freq - 11300. The Sat is OPTUS D1-T5L (STB s/w is A350).

I used a compass and aimed the dish at 316 MAG, using the guide on the mount I set the inclination to 45. The SKEW is about 80.
I connected the SAT meter and turned on the STB.
To get a reading / tone on the meter I have to turn it right up.
I then turn it down until I just loose the tone. If I put my hand in front of the LNB I get full deflection and tone.
I then sit behind the dish and try moving it left/right up/down from its original position but get no increase in the reading.
I am slowly moving in a range of about +/- 30 degrees.
The Pace STB shows a strength of 73 and 0 quality.

I'm usually pretty good at this sort of stuff but am really pulling my hair out over this one! All the guides and info I have found make it sound so easy.

Cheers

xcubed

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#102398 31-Dec-2007 15:30

It all depends on your location, which you haven't mentioned.

You can calculate the dish angles you need at: http://www.freeviewshop.co.nz/dish-angle-calculator-i-16.html

slotherby

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#102402 31-Dec-2007 16:16

I am in Auckland, hence why I am using 316 & 45 degrees.

cyril7

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#102451 1-Jan-2008 09:32

The beamwidth of a 65cm dish is around 3deg, ie the half power points are 1.5deg eitherside of the peak. You are being pretty hopefull to just put the dish up and expect it to be there. The signal finder should pin itself when you find the signal. You need to try various elevations not just 45deg, you also need to adjust the skew. I suggest you loosen off the bolts so that you can swing the dish freely in the approximate settings you have noted, a few quick sweeps and you will find it.

In fact take the dish off the mount and swing it about, after a few minutes you should find a loud pip on the finder to assure you its definitely there, then remount.

Cyril

slotherby

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#102454 1-Jan-2008 09:50

I'm trying different positions from my starting point. Left/Right Up/Down. But I just can't seem to get a signal, if I tilt it down towards the roof I get a signal, if I put my hand in front of the LNB I get a signal but if I slowly move it around in the direction I think the satellite should be I get nothing. I'm easily covereing an azimuth of +/- 30 degrees and an elevation of +/- 20 degrees, I'm moving it slowly and in small increments - but no luck.

The info I have found talks about satellite elevation (44.5) and dish elevation (depends on dish type and size). Am I right in assuming the the graduated markers on the side of the mount relate to a satellite elevation for my dish? I'm only using this figure as a starting reference point.

I have set the Skew of my LNB to look like this as this is what my LNB looks like, except its a grey colour instead of black.
http://www.freeviewshop.co.nz/forum/index.php/topic,136.0.html

Cheers
Paul

richms

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#102493 1-Jan-2008 16:13

The pole is level?

ANd some dishes have 2 ways up that part of the bracket can go to get 2 ranges of elevations, you need to look at the right scale (assuming it has 2 of them)

Otherwise all I have done in the past is lock in the elevation to 45° and aim it by eye with a neighbours dish and thats being enough to get lock, then tweek it with the onscreen meter.

Richard rich.ms

slotherby

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#102512 1-Jan-2008 21:27

That's why I am banging my head! You make it sound so easy.

I checked the pole was level, then I took Cyril's advice and took the dish off the pole and aimed it that way, got good tone on the meter. Put the dish on the pole and tweaked its alignment until I had the best tone with the lowest gain. Climbed off the roof and found the strength had gone from its normal 73 up to 81 but no "lock on' and no quality. Climbed back up the roof and tried the whole process again, was feeling very confident that I had it this time, climbed down to see the strength back at 73. Its driving me mad.

I'm wondering whether I have a dud LNB. I know the receiver works as its my folks one and the cable has no shorts and is a reasonable length - probably only 10-15m.

Time to call in the pro's I think.

Lenovo

Shop now for Lenovo laptops and other devices (affiliate link).

richms

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#102513 1-Jan-2008 21:30

It is easy, thats the thing, I recon you have something fautly there. Is there any change in level when you change the set top between vertical and horizontal?

Richard rich.ms

slotherby

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#102514 1-Jan-2008 21:33

richms: change the set top between vertical and horizontal?

What do you mean?

Paul

richms

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#102518 1-Jan-2008 22:18

When you are adding the transponder to tune to, you need to put a polarity, if you have it wrong there should be a lot less signal, in any case there should be a change in signal between the 2 settings, often a stuffed lnb is stuck on one setting and not changing so you dont see a change in level.

Richard rich.ms

slotherby

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#104477 13-Jan-2008 09:13

Hi all

Just to close this thread off, I ended up calling in a pro who turned my dish to the left and lowered it a bit and voila! It seems that my crappy old compass (which has found a lovely new home in a bin) was about 20 degrees out - was showing closer to True North rather than Mag North.

Anyway as soon as that was done I was able to follow some of the other threads and get Vista Media Centre all up and running and so now have a lovely clear picture on my 47" LCD.

Thanks everyone for your efforts.

Paul

grant_k

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#104501 13-Jan-2008 12:00

slotherby: ...It seems that my crappy old compass (which has found a lovely new home in a bin) was about 20 degrees out - was showing closer to True North rather than Mag North.

The offset between True North and Magnetic North in this part of the world during 2007/8 is about 18.5 degrees, which may account for what you observed.